Sum of First n Terms of an AP

Find how many terms of the arithmetic progression $3,6,9,\dots$ must be added to get the sum $165$ .

If $a_3=15$and $S_{10}=125$, then find the value of $d$ and $a_{10}$

If $a=7$and $a_{13}=35$, then find the value of $d$ and $S_{13}$

A $4^{th}$ term of an AP is $9$ and its $9^{th}$ term is $34$. The sum of the first $10$ terms of the AP is _____.

Find the sum of all natural numbers from $1$ to $1000$ which are neither divisible by $2$ nor by $5$.

The sum of $₹700$ is to be used to give seven cash prizes to students of a school for their overall academic performance. If each prize is $₹20$ less than its preceding prize, Find the value of each of the prizes.

Find the sum of first $15$ terms of $3+6+9$ .................. using the formula

The sum of $n$ terms of an A.P. is $3n^2+5n$, then its first term is

The sum of the first $100$ natural numbers is

Sachin invested some amounts in National Saving Certificates in a specific way. In the first year he invested $₹4,000$, in the second year $₹6,000$, in the third year $₹8,000$ and so on for $12$ years. Find the total amount (in $₹$) he invested in $12$ years.

Find the sum of the series $3+7+11+ .......$ to $10$ terms.

Find the sum of all two digit positive integers which are divisible by $3$ but not by $2$.

Find the sum of the first twenty terms of Arithmetic series $2+7+12+...$ 

Sum of all the first $\text{'}n\text{'}$ terms of even natural number is

If second and third terms of an Arithmetic Progression are $3$ and $5$ respectively, then find the sum of first $20$ terms of it.

For an A.P., find $S_{10}$ if $a=6$ and $d=3$.

If $S_5=15$ and $S_6=21$, find $t_6$.

Find the sum of all two-digit odd multiples of $3$. 

Sachin invested some amounts in National Saving Certificates in a specific way. In the first year he invested $₹4,000$ in the second year $₹6,000$ in the third year $₹8,000$ and so on for $12$ years. Find the total amount (in $₹$) he invested in $12$ years.

Find the sum of $5+8+11+...$ upto $10$ terms.